Okay, after seeing the most recent posts in this thread, and knowing I have many dozens of more hours of entertainment awaiting in STARFIELD over the next few weeks anyway, I bit the bullet today after work and re-enrolled in the Beta. This time I made some timings to document actual loading performance of the latest build. I have a pretty good amount of Marketplace and Community folder content and I did NOT specifically disable or uninstall any of it for the purposes of the test. Start time measured from double-clicking the desktop shortcut on my PC. Sim and all associated content is installed on an m.2 NVME SSD. Core i7-11700K, 32GB DDR4 3600 memory.
Current mainline (non-Beta) build: 5:32
After restarting, updating the MSFS sim, then pulling in the in-sim update to the Beta build (~4GB), time from completing that update to main menu: 4:52
First load into the PMDG 737-800, at gate E8 of iniBuilds PHNL: 2:14
First load into the PMDG 737-700, at gate E8 of iniBuilds PHNL: 2:17
Second load of the -800: 0:27
Second load of the -700: 0:25
After restarting the PC again and loading the Beta: 5:35
So it seems to me that for my content, loading times are back to normal and best of all, I did not experience CTDs after clicking the yellow Fly Now button.
Another observation/disclaimer: the initial load time of the SU13 Beta above is artificially low because it was only timed AFTER the initial 30 odd second load to the point of checking for updates, then however long it takes to decide there are none available and proceeding on. For the first load, this step is what resulted in the actual update of the main files to the current Beta. The baseline release time above, as well as the second load time for the Beta, both include that step and are entirely on par with one another with the same (*) content.
(*) ANOTHER DISCLAIMER: after updating to the Beta, I had about 5GB of content manager updates, which seemed to be several World Update POIs. This was odd to be as as I not get prompted for those updates when I loaded into the baseline release of the sim. Even odder, at one point when I canceled out of a flight back to the menu to test load times for another plane, I was prompted for ANOTHER update to a World Update POI package. I did not load into the sim a third time to see if there were more content updates again.